1. Field of the Invention
The inventions disclosed and taught herein relate generally to solenoid controlled valves; and more specifically relate to solenoid controlled pilot operated valves for air service.
2. Description of the Related Art
U.S. Pat. No. 5,676,342 discloses a “proportional flow valve wherein inlet fluid pressure urges a main valve unit having a main valve member and a surrounding diaphragm toward the valve seat. The diaphragm is connected to the valve body and has a bleed passageway to enable inlet fluid to pass from an inlet port below the main valve unit to a reservoir above it. The area of the main valve unit exposed to the reservoir is substantially greater than the area of the main valve unit exposed to the inlet port. A solenoid actuator determines the position of a pilot valve sealing member which controls the flow of inlet fluid from the reservoir through a pilot opening in the main valve member to an outlet port to selectively relieve the pressure above the main valve unit thereby permitting the main valve unit to move away from the main valve seat.”
U.S. Pat. No. 6,601,821 discloses a “two-stage proportional control valve assembly regulates flow of a first fluid such as an engine exhaust gas using a second fluid such as engine oil for power. A directional valve under control of an electrical actuator regulates flows of the second fluid to operate a fluid-powered actuator. A mechanical connection between the fluid powered actuator and a flow control valve for regulating flows of the first fluid enables the electrical actuator to indirectly control the flow control valve with a minimum draw.”
U.S. Pat. No. 6,883,320 discloses a “servomechanism for a valve controlling engine intake flow via a cooler and a bypass uses a proportional solenoid operating a hydraulic valve to power a hydraulic actuator setting the position of the control valve. An engine sensor and electric controller provide input to the proportional solenoid, and feedback from the position of the control valve is applied to the hydraulic valve by a cam and spring applying a force in opposition to the proportional solenoid.”
International Publication No. WO 01/61226 discloses an “extended range proportional valve (10) which can control rates of mass flow over continuous low, intermediate, and high ranges has a pilot member (68) mounted on an armature (84) of a solenoid which can be dithered onto and off of a pilot opening (58) in a main valve member (30) which seals a main valve opening (18) to control mass flow rates over the low range by varying the duty cycle and/or frequency of a pulse width modulated current in the solenoid coil. Intermediate and high flow rates are achieved by dithering the pilot valve member (68) with a duty cycle and/or frequency sufficient to raise the main valve member (30) relatively short and relatively long respective distances from the main valve seat (18).”
An ASCO Valve, Inc. catalog, dated Feb. 2008, discloses, among other things, a compact positioner that “[v]aries flow proportional to a 0-10 VDC, 0-20 mA or 4-20 mA control signal.”
The inventions disclosed and taught herein are directed to an improved solenoid controlled pilot operated valve.